Managing vaccine supply chain improvements involves a complex interaction of laboratories, other facilities, CMOs, and suppliers. Since the business of making vaccines became a commercial proposition, profitability has often been elusive. The economics are difficult: Costs of development and production, already high, are rising. Profit margins historically have been lower than those of other pharmaceutical products, in part because of the complexities of manufacturing and distributing vaccines as well as their stringent safety, testing, and quality requirements.